from datetime import datetime from jinja2 import BaseLoader, Environment, StrictUndefined, TemplateError DEFAULT_PAYMENT_METHODS = [ "bank_transfer", "cash", "credit_card", ] AVAILABLE_TEMPLATE_VARIABLES = [ "company_name", "invoice_number", "invoice_date", "due_date", "customer_name", "customer_contact_name", "customer_email", "customer_phone", "customer_mobile", "customer_address", "currency", "subtotal", "total_tax", "total_amount", "notes", "issued_at", "payment_methods", "payment_methods_text", "items", ] DEFAULT_INVOICE_EMAIL_SUBJECT_TEMPLATE = "Invoice {{ invoice_number }}" DEFAULT_INVOICE_EMAIL_BODY_TEMPLATE = """Hello {{ customer_name }}, Please find attached invoice {{ invoice_number }}. Invoice date: {{ invoice_date }} Due date: {{ due_date }} Amount due: {{ currency }} {{ total_amount }} {% if notes %}Notes: {{ notes }} {% endif %}Regards, {{ company_name }}""" DEFAULT_INVOICE_TEMPLATE = """

Invoice

INVOICE

{{ invoice_number }}

Invoice Date

Due Date

Bill To

{% if customer_contact_name %}

{% endif %} {% if customer_email %}

{% endif %} {% if customer_phone %}

{% endif %} {% if customer_mobile %}

{% endif %} {% if customer_address %}

{% endif %}

Amount Due

{% for item in items %} {% endfor %}

Description	Qty	Unit Price	Tax	Subtotal	Total
{{ item.description }}	{{ item.quantity }}	{{ currency }} {{ item.unit_price }}	{{ item.tax_rate_percent }}	{{ currency }} {{ item.subtotal }}	{{ currency }} {{ item.total }}

Subtotal{{ currency }} {{ subtotal }}

GST{{ currency }} {{ total_tax }}

Total{{ currency }} {{ total_amount }}

{% if notes %}

Notes

{% endif %}

Payment Methods

{{ method }}

""" def _format_money(value) -> str: return f"{float(value or 0):.2f}" def _load_payment_methods(db) -> list[str]: from app.core.models import SystemConfig row = db.get(SystemConfig, "invoice_payment_methods") raw = row.key_value if row and row.key_value else ",".join(DEFAULT_PAYMENT_METHODS) parts = [part.strip() for chunk in raw.splitlines() for part in chunk.split(",")] methods = [part for part in parts if part] return methods or list(DEFAULT_PAYMENT_METHODS) def _load_template_source(db) -> str: from app.core.models import SystemConfig row = db.get(SystemConfig, "invoice_template_html") if row and row.key_value and row.key_value.strip(): return row.key_value return DEFAULT_INVOICE_TEMPLATE def _load_email_subject_template(db) -> str: from app.core.models import SystemConfig row = db.get(SystemConfig, "invoice_email_subject_template") if row and row.key_value and row.key_value.strip(): return row.key_value return DEFAULT_INVOICE_EMAIL_SUBJECT_TEMPLATE def _load_email_body_template(db) -> str: from app.core.models import SystemConfig row = db.get(SystemConfig, "invoice_email_body_template") if row and row.key_value and row.key_value.strip(): return row.key_value return DEFAULT_INVOICE_EMAIL_BODY_TEMPLATE def _build_context(invoice, items, customer, payment_methods: list[str]) -> dict: primary_contact_name = getattr(customer, "contact_name", "") if customer else "" customer_name = getattr(customer, "company_name", "") or getattr(customer, "name", "") or "Unknown" normalized_items = [] for item in items: normalized_items.append( { "description": item.description or "Item", "quantity": f"{float(item.quantity or 0):.2f}", "unit_price": _format_money(item.unit_price), "tax_rate": f"{float(item.tax_rate or 0):.4f}", "tax_rate_percent": f"{float(item.tax_rate or 0) * 100:.1f}%", "subtotal": _format_money(item.subtotal), "total": _format_money(item.total), } ) return { "company_name": "ERP System", "invoice": invoice, "customer": customer, "items": normalized_items, "invoice_number": invoice.invoice_number, "invoice_date": str(invoice.invoice_date), "due_date": str(invoice.due_date or "Upon receipt"), "customer_name": customer_name, "customer_contact_name": primary_contact_name, "customer_email": getattr(customer, "email", "") if customer else "", "customer_phone": getattr(customer, "phone", "") if customer else "", "customer_mobile": getattr(customer, "mobile", "") if customer else "", "customer_address": getattr(customer, "address", "") if customer else "", "currency": invoice.currency, "subtotal": _format_money(invoice.subtotal), "total_tax": _format_money(invoice.total_tax), "total_amount": _format_money(invoice.total_amount), "notes": invoice.notes or "", "issued_at": datetime.now().strftime("%Y-%m-%d"), "payment_methods": payment_methods, "payment_methods_text": ", ".join(payment_methods), } def render_invoice_html(db, invoice, items, customer) -> str: template_source = _load_template_source(db) payment_methods = _load_payment_methods(db) context = _build_context(invoice, items, customer, payment_methods) environment = Environment( loader=BaseLoader(), autoescape=True, undefined=StrictUndefined, ) try: template = environment.from_string(template_source) return template.render(**context) except TemplateError as exc: raise ValueError(f"Invoice template error: {exc}") from exc def render_invoice_email(db, invoice, items, customer) -> tuple[str, str]: payment_methods = _load_payment_methods(db) context = _build_context(invoice, items, customer, payment_methods) environment = Environment( loader=BaseLoader(), autoescape=False, undefined=StrictUndefined, trim_blocks=True, lstrip_blocks=True, ) try: subject_template = environment.from_string(_load_email_subject_template(db)) body_template = environment.from_string(_load_email_body_template(db)) subject = subject_template.render(**context).strip() body = body_template.render(**context).strip() return subject, body except TemplateError as exc: raise ValueError(f"Invoice email template error: {exc}") from exc def generate_invoice_pdf(db, invoice_id: int) -> bytes: """Generate PDF bytes for an invoice with a configurable HTML template.""" try: from weasyprint import HTML except (ImportError, OSError) as exc: raise ImportError( "WeasyPrint not available: missing system libraries. " "Install with: apt-get install libpango-1.0-0 libpangocairo-1.0-0 " "libgobject-2.0-0 libcairo2 fonts-dejavu" ) from exc from app.core.models import Customer, Invoice, InvoiceItem invoice = db.query(Invoice).get(invoice_id) if not invoice: raise ValueError("Invoice not found") items = db.query(InvoiceItem).filter(InvoiceItem.invoice_id == invoice_id).all() customer = db.query(Customer).get(invoice.customer_id) html = render_invoice_html(db, invoice, items, customer) return HTML(string=html).write_pdf()